1. Field of the Invention
Embodiments of the processes and systems of this invention are designed for the efficient conversion of thermal energy from the exhaust flue gas stream, such as flue gas stream from a gas turbine, but equally to any hot flue gas stream, into useful electrical power. The processes and systems of this invention are thus bottoming cycles for combined cycle systems.
More particularly, embodiments of the processes and systems of this invention relate to the efficient conversion of a portion of the thermal energy in a hot external gas stream into a useable from of energy, where the system includes two sub-systems, a boiler-turbine sub-system in which a condensed working is vaporized or vaporized and superheated by a gaseous external heat source stream and a portion of its thermal energy is converted via a turbine component into a useable form of energy such as electric power, and a condensation thermal compression sub-system (CTCSS), where a spent working solution stream is condensed at reduced pressure, i.e., at pressure which is lower than the pressure of condensation achievable at any given ambient temperature, to from a rich solution stream and a lean solution stream that are heated in lowers sections of the boiler component to form streams that when mixed from a working solution stream where the temperature of the two streams and the combined stream are equal or substantially equal as that term is defined herein.
2. Description of the Related Art
Power systems with thermodynamical power cycles utilizing multi-component working fluids can attain a higher efficiency than power systems utilizing single-component working fluids. Multi-component working fluids condense at variable temperatures. Such working fluids, unlike single component working fluids, have a thermodynamical potential to perform useful work even when sent into a condenser after expansion in a turbine.
Therefore, in the prior art, several power systems that utilized a multi-component working fluid, were designed to have condensation occur in special subsystems which were referred to as distillation condensation subsystems. In this application, such a subsystems will be referred to as a Condensation and Thermal Compression Subsystems (CTCSS), a term that more accurately describes the nature of such subsystems. Such subsystems all work on the following principle: A stream of working fluid subject to condensation enters into the CTCSS at a pressure which is substantially lower than the pressure required for the complete condensation of such a stream at a given ambient temperature. The stream of working fluid is mixed with a recirculating stream of lean solution (i.e., a stream with a substantially lower concentration of the low-boiling component), forming a new stream which can be fully condensed at the given ambient temperature, (referred to as the “basic solution”). Thereafter, the basic solution stream is pumped to a pressure which is slightly higher than the pressure required for the condensation of the working fluid, and is subjected to partial re-vaporization, for which heat that was released in the process of condensation is utilized. Then, the partially vaporized basic solution stream is separated into a lean liquid stream having a reduced concentration of the low-boiling component and a rich vapor stream having a higher concentration of the low-boiling component. The lean liquid stream is then mixed with the condensing stream of working solution (as described above), while the rich vapor stream is combined with a portion of the basic solution stream to reconstitute the initial composition of the working fluid, which is then fully condensed.
In U.S. Pat. No. 4,489,563, the most basic and elementary CTCSS has been described. In this very simple CTCSS, heat from rich vapor stream and lean liquid stream produced by partial re-vaporization is not recuperated, drastically reducing the efficiency of this simple CTCSS.
Although other CTCSS have been disclosed such as those set forth U.S. Pat. Nos. 4,548,043; 4,586,340; 4,604,867; 4,763,480; 5,095,708; and 5,572,871, these CTCSS systems are more complicated and elaborate and cannot be easily modified to improve their efficiency or the efficiency of an overall energy extraction system, where the patent are incorporated by reference by the operation of the closing paragraph of the Detailed Description of the Invention.
More recently, newer CTCSS configurations have been disclosed such as those set forth in U.S. Pat. Nos. 7,043,919 and 7,197,876, which are incorporated by reference by the operation of the closing paragraph of the Detailed Description of the Invention. However, there is still a need in the art for a Condensation and Thermal Compression Subsystem (CTCSS) and systems based on it with improved efficiency of the energy extraction process from gaseous heat source streams.